With the recent rapid expansion of the market for portable electronic equipment (such as PDAs and mobile telephones), accompanied by development of small-sized apparatuses, there are increasing demands for disk drive apparatus as one of the data storage means in such equipment having enhanced portability, namely that are small-sized and low-profiled, and having higher shock resistance and reliability. There have been proposed various methods for disk drive apparatus meeting such demand for high shock resistance.
As an example of a conventional disk drive apparatus including a head, a conventional disk drive apparatus in a magnetic recording and reproducing apparatus such as a hard disk drive apparatus will be described with reference to the accompanying drawings.
FIG. 9 is a plan view showing a configuration of a conventional magnetic recording and reproducing apparatus. In FIG. 9, head supporting assembly 108 is made up of suspension 102 and plate spring portion 103, which are relatively low in rigidity, and supporting arm 104 relatively high in rigidity. On the underside of one end of suspension 102, there is provided slider 101 with a magnetic head (not shown) mounted thereon.
Magnetic recording medium 107 is provided so as to be rotated by spindle motor 109. When recording/reproduction is performed by the magnetic recording/reproducing apparatus, the magnetic head mounted on slider 101 is allowed to fly at a predetermined distance above magnetic recording medium 107 depending on the relationship between a lifting force caused by an airstream generated on slider 101 due to rotation of magnetic recording medium 107 and an urging force produced by head supporting assembly 108 to urge slider 101 toward magnetic recording medium 107. At the time of recording/reproduction, head supporting assembly 108 is rotated around bearing portion 105 by action of voice coil 106 provided on supporting arm 104 and, meanwhile, the magnetic head mounted on slider 101 is positioned into a desired track on magnetic recording medium 107 so that recording/reproduction is performed.
The magnetic recording and reproducing apparatus shown in FIG. 9 is on the contact-start-stop system, as generally called, (hereinafter referred to as the CSS system). The system is characterized by that, while magnetic recording medium 107 is stopped, the magnetic head is on magnetic recording medium 107 in contact therewith, and while recording/reproduction is performed, the magnetic head provided on slider 101 is lifted up from magnetic recording medium 107. In such CSS system, magnetic recording medium 107 is divided into region A that is magnetically recordable and region B to which the magnetic head is retreated during a non-rotation period as shown in FIG. 9. When the rotation of magnetic recording medium 107 is to be stopped, the magnetic head lifted up is first shifted into region B and then the rotating speed is lowered, whereby the airstream between magnetic recording medium 107 and slider 101 is reduced to decrease the lifting force and, finally, the magnetic head comes into contact with magnetic recording medium 107 to be stopped in this state.
Therefore, magnetic recording medium 107 in the CSS system is arranged such that the surface of region B is formed rougher than the surface of region A to thereby prevent occurrence of such a trouble that the magnetic head adheres to magnetic recording medium 107 at the time when magnetic recording medium 107 stops its rotation, and hence, at the time of restarting, magnetic recording medium 107 suffers mechanical and magnetic damage.
As another method for supporting the head, there is the load-unload system (hereinafter referred to as the L/UL system). FIG. 10 is a perspective view showing a magnetic recording and reproducing apparatus on the L/UL system. In FIG. 10, head supporting assembly 108 has a configuration similar to that of head supporting assembly 108 of the CSS system shown in FIG. 9. In this case, however, when the magnetic recording and reproducing apparatus is stopped, head supporting assembly 108 is rotated around bearing portion 105 to be shifted to the outside of magnetic recording medium 107. In this case, since there is provided magnetic head supporting portion 110 outside magnetic recording medium 107, projected portion 111 provided at the front end of suspension 102 is caused to land on the tapered portion so that slider 101 and the magnetic head come to be supported thereon separated from magnetic recording medium 107.
In the head supporting assembly of the magnetic recording and reproducing apparatus, the urging force to urge the slider toward the magnetic recording medium with a predetermined load is chiefly developed by the plate spring portion, while the suspension is configured to have flexibility. This is for allowing the slider to stably fly up even when the disk produces up-and-down movements when recording/reproduction is performed on the disk so that the head is prevented from coming off a predetermined track position, i.e., from exhibiting the so-called off-track phenomenon, and also for allowing the head to certainly follow up-and-down movements of the disk. Therefore, it is required that the urging force necessary for urging the slider toward the disk be certainly secured by the plate spring portion.
Further, when manufacturing variations are produced in the suspension, the urging force urging the head toward the disk by the plate spring portion configured by bending the suspension portion may vary. In order to stably maintain the distance between the head and the disk by having such variations absorbed, it is required to further lower the rigidity of the spring portion of the suspension. However, if the rigidity of the spring portion of the suspension is lowered, the resonance frequency of the suspension is lowered, and thereby an unstable phenomenon in which bending or twisting vibration mode is produced occurs to cause the off-track trouble of the head.
Further, in the conventional head supporting mechanism, its center of gravity is positioned closer to the portion where the head is mounted than the plate spring portion. Therefore, when the magnetic recording and reproducing apparatus is subjected to an external shock or the like, the balance of force at the slider portion between the lifting force due to the airstream generated by the rotation of the disk and the urging force to urge the slider toward the disk is lost and such a phenomenon of the slider jumping off the disk surface tends to occur. When such jumping occurs, the slider sometimes collides with the disk to cause magnetic or mechanical damage to the disk. Such problems occur not only in the above described magnetic recording and reproducing apparatus but also in other disk drive apparatus having a floating head such as an optical disk drive apparatus and a magneto-optic disk drive apparatus.
The present invention was made to overcome the above mentioned problems and it has an object to provide a head supporting assembly, as well as a head driving assembly, capable of securing stabilized urging force not affected by manufacturing variations and that is excellent in shock resistance, and to provide a disk drive apparatus using the same.